PROJECT SUMMARY Glaucoma is a leading cause of blindness in the world, affecting over 60 million people. Extensive research has demonstrated that increased intraocular pressure (IOP) results in a progressive loss of ganglion cells that is subsequently expressed as a loss of vision. The exact relationship between the chronic dynamics of IOP and the damage experienced by the eye is still unknown and is the central focus of glaucoma studies across the world. Over the years, scientists have developed several animal models in which a wide variety of methods is used to damage the drainage pathways of the eye so that fluid cannot get out as easily. Such techniques tend to be time consuming, present a low success rate, last permanently, and offer no control over IOP amplitude or dynamics. All of these issues significantly hamper our continued ability to study the causes and effects of the disease. Current technology to monitor IOP is also a limiting factor. Tonometry, the most used technique to measure IOP, yields insufficient data and requires a skilled operator at all times. Implantable sensors have been commercially developed to address the issue but they rely on battery power to function, which limits their operating lifetime and the accuracy of the data collected. This project describes one-of-a-kind wireless implantable devices that are capable of continually measuring and regulating IOP, doing so with high accuracy, near-zero failure rate, and virtually unlimited operational lifetime. For the first time they give the experimenter complete control over the IOP history to which an eye is exposed. This project proposes to use the technology to investigate the response and resiliency of the eye to elevated IOP when fluid drainage pathways are not overtly damaged like in all other animal models of the disease. The specific aims are to systematically and quantitatively assess the effects of experimental glaucoma and this new perfusion-induced hypertension model on: i) IOP variability, ii) ocular fluid dynamics, iii) retinal structure and function, and iv) visual sensitivity of rats.